Bladder catheter

ABSTRACT

A bladder catheter for transurethral introduction into the urinary bladder by the urethrae, includes an elastic catheter shank with a fillable balloon element secured thereto and connected to a filling channel incorporated into the wall of the catheter shank. The balloon element and the catheter shank are made of polyurethane, a polyurethane-polyvinylchloride mixture or similar polyurethane-based material.

FIELD OF THE INVENTION

The present invention is directed to a bladder catheter fortransurethral introduction into the urinary bladder through the urethra,composed of a flexible catheter shaft having a refillable balloonelement secured thereto, which communicates with a filling channelintegrated in the wall of the catheter shaft.

BACKGROUND

When providing health care, the use of bladder catheters is oftenrequired. Bladder catheters in use today are composed of a flexiblecatheter shaft, to whose distal end, which is placed in the urinarybladder, a fluid-refillable balloon element is fastened. The cathetershaft has a filling channel, which leads into the balloon interior viaan opening in the catheter wall. The main purpose of the balloon elementis to securely mechanically anchor the catheter in the urinary bladder.In addition, when placed in the opening of the bladder, the balloon hasa certain sealing function and prevents urine from flowing out of thebladder, past the catheter and through the urethra.

In the unfilled state, the balloon element resembles a sleeve pulledover the catheter shaft, fitting on the shaft all-around, typicallyunder slight tensioning, in any case, however, in a fold-free manner.The sleeve is comparable to a hose fitting, and is usually fabricatedfrom the same material or a substantially identical material as theshaft, but is modified in its elongation properties. Conventionalballoon elements are designed with this specific type of construction,which, in the emptied state, fits closely on the shaft, to enable theballoon element to be advanced with as little as possible resistance,through the urethra into the bladder lumen. In this way, painfulirritations or lesions of the urethra's mucous membrane, caused by foldsor bulges in the wall of the balloon element that previously existed orformed during the advancing motion, are avoided when inserting thecatheter. Once the balloon element is securely introduced into thebladder, the sleeve (balloon element) closely fitting on the shaft, iselastically expanded into a balloon by a fluid, under relatively highpressure. The material typically selected for the catheter shaft and theballoon element of conventional catheters, latex or silicon, permits anelastic expansion of the balloon element to a volume of 5 and 30 ml,respectively. These are the two standard balloon volumes for bladdercatheters used in clinical practice.

Ideally, the balloon element, that has been elastically expanded into aballoon, fully retracts, even after a longer-term use of the catheter,and closely fits on the catheter shaft as a sleeve-type hose fitting,without forming folds or bulges. In this way, the drained balloonelement does not cause any painful irritation or trauma to the sensitiveurethra epithelium even during removal of the catheter. Typically,however, the balloon element, that has been elastically expanded for anextended period of time into a balloon, is not able to be fullyelastically retracted onto the shaft. The partial loss of the sleeveelasticity caused by an elastic expansion of the balloon element overseveral days can be accelerated by the action of chemically aggressiveurinary components (e.g., uric acid). In the case of latex-basedcatheters, given a long-period use, the urine regularly leads to apronounced stiffening of the balloon element, but also to a considerableloss of elasticity of the catheter shaft. Once drained, balloon elementsof the known type of construction, having a latex- or silicon-basedsleeve, often exhibit residual, coarse folds or bulges in the (notfully) retracting envelope, and pose a considerable risk of injury tothe patient.

Moreover, catheter materials customarily used up to now (latex, silicon,or latex- or silicon-based materials, and/or composite materials made oflatex and silicon) have other clinically relevant disadvantages.

One drawback (particularly when latex materials are used) is that theballoon element does not always open out symmetrically with respect toform when elastically expanding and can burst in response to slightlateral weighting. The stability of the balloon anchoring in the openingof the bladder can be adversely affected by a pronounced asymmetry ofthe balloon with respect to form. Moreover, a pronounced asymmetry ofthe filled balloon element, depending on its placement in the opening ofthe bladder, can cause the catheter lumen to snap off.

A further disadvantage is that the balloon element of catheters of aconventional type of construction, as necessitated by theparticularities of the manufacturing and the material, must remain belowspecific wall thicknesses. The minimum wall thickness of the elasticallyexpanding sleeve, when filled to form the balloon, must be such that itis able to avoid, with certainty, falling below a lower, criticalminimum wall thickness, below which the danger of rupture exists, inresponse to increasing shaping-out of the balloon (and the reduction inthe balloon wall thickness accompanying the elastic expansion). Theminimum wall thickness of the balloon element that fits on the shaft inthe manner of a sleeve is typically within the range of at least 100micrometers and requires relatively high pressures when the sleeveundergoes elastic expansion or deformation. During expansion, theballoon element assumes a shape predominantly in the radial, but also inthe longitudinal direction (elongation). With increasing filling volume,the pressures forming in response to the predominantly radial elasticexpansion of the balloon envelope in many cases cause a compression orstenosis of the drainage lumen of the catheter. This lumen-narrowingeffect is furthered by the likewise occurring elastic expansion of theballoon in the longitudinal direction and, as a consequence thereof, theelongation of the catheter shaft in the balloon region. Both elongationcomponents can lead to a considerable narrowing or stenosis of thecatheter lumen.

It is a complex process to manufacture conventional bladder catheters,and one that requires many individual steps. In many cases, theparticular dipping or molding processes do not ensure a satisfactorysurface quality of the catheter and balloon. Above all, the siliconprocessing yields slightly rough and irregular boundary surfaces. Thispromotes the incrustation of urinary components, as well as thebacterial colonization of catheter surfaces.

The particular difficulty also arises when silicon is used, of watersubstantially permeating through the balloon envelope. To ensure thatthe balloon is adequately filled, it must typically be refilled in analmost daily cycle.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a bladder catheterwhich will be able to be simply manufactured from a standpoint ofproduction engineering and, which will benefit the patient overlong-term catheter use, and which avoids disadvantages of knowncatheters.

The present invention provides a bladder catheter for transurethralintroduction into a urinary bladder that includes a flexible cathetershaft having a wall; a filling channel integrated into the wall; and aballoon element, wherein the balloon element and the catheter shaft aremade of a polyurethane-based material, such as a polyurethane, apolyurethane-polyvinyl chloride blend, or of a comparable,polyurethane-based material. It is, in fact, already known tomanufacture a polyurethane shaft using the extrusion method for bladdercatheters, and the method has been tried and tested in clinicalapplications on patients. However, due to its inadequate elongationproperties, polyurethane was considered unsuitable for balloon elementsof conventional design types.

For that reason, catheters having a polyurethane shaft were provided inknown methods heretofore with balloon elements of latex or silicon or ofrelated, similarly volume-expandable materials. A polyurethane sleevethat is pulled over the shaft (typical shaft diameter of approximately 4to 6 mm for adults) and fits closely thereon, could only be elasticallyexpanded to a balloon of a sufficient size (filling volume 5 or 30 ml)under very high pressure, which was only be able to be conditionallyproduced by the user using conventional means. The stresses produced inthe wall of the balloon being shaped out would be considerable in anycase. The drainage lumen of the catheter would be substantiallyconstricted by the immense balloon filling pressure, as previouslydescribed.

Surprisingly, it turns out, however, that a polyurethane balloon elementmay nevertheless be used when manufacturing a bladder catheter,particularly when the balloon element is preformed into a balloon, as aballoon film having a wall thickness of 5 to 20 micrometers, preferably5 to 15 micrometers. The preferably partially preformed base-stateballoon in accordance with the present invention fits closely on theshaft wall in the empteied state, its envelope being folded. Thepreformed base-state balloon is provided in a generally known mannerwith two shaft pieces via which it is fastened to the catheter shaft.There is no need in accordance with the present invention to reduce theshaft diameter which allows for the base-state balloon that sits or laysfolded on the shaft. The user may select the shaft thickness of thecatheter in the usual manner and without any restrictions.

To conform to the catheter types in use today, the present inventionproposes two basic, partially preformed, so-called base-state balloontypes, which, in the completely filled, fully formed state (workingballoon) have a filling volume of 5 ml or 30 ml.

To be able to achieve a working filling volume of 5 ml using fillingpressure values that do not compromise the catheter shaft, thebase-state balloon is designed in such a way that, in the unexpandedat-rest or base state, i.e., when the balloon is filled to the freelyunfolded at-rest or base-state form (preferably spherical or spindleform), it has an at-rest or base-state volume of approximately 1.2 to2.5 ml. In this filled base state, the cuff envelope is stillunexpanded.

The balloon is preferably fastened to the shaft in the longitudinallyextended form. In the process, the shaft pieces of the balloon are fixedto the shaft in such a way that they are maximally spaced apart, whileavoiding a tensile stretching of the balloon envelope. The balloonenvelope orients itself in a shaft-parallel lengthwise fold formation,and clings closely to the catheter shaft. The remaining at-rest fillingvolume in the balloon fastened in this manner, is typically less than0.05 ml, preferably within the range of only 0.01 to 0.03 ml.

In the case of the specific embodiment of the 5 ml working fillingvolume, the wall thickness of the balloon envelope is preferably withinthe range of from 5 to 10 micrometers.

Given a larger working filling volume of, for example, 30 ml, in theunexpanded base state, i.e., when filling the balloon to the freelyunfolded at-rest form (preferably cylindrical or spherical form), thebase-state balloon receives a volume at rest of approximately 4 to 10ml. The balloon is preferably fastened to the shaft in thelongitudinally extended form (in the manner corresponding to the 5 mlballoon). The at-rest volume of the cuff applied in this manner istypically less than 0.08 ml, preferably in the range from only 0.02 to0.04 ml. In the case of the specific embodiment of the 30 ml workingfilling volume, the wall thickness of the balloon envelope is preferablywithin the range of from 5 to 15 micrometers.

The polyurethane polymer used, the uninflated volume of the base-stateballoon, and the wall thickness of the balloon are selected in such away that the safety range of volumetric expandability of the balloon ispreferably 300 to 400 percent and does not exceed a safety range of from400 to 450 percent.

The balloon envelope that forms longitudinal or also unaligned foldsallows a partially preformed base-state balloon to be elasticallyexpanded to the filled working balloon in that comfortable pressurevalues are applied which do not constrict the catheter lumen. In thecase of the preformed balloon according to the present invention, thefilling pressure is typically only 50-200 mbar (given 5 ml workingvolume) and 50-250 mbar (given 30 ml working volume), respectively.

For the balloon according to the present invention, Pellethane 2363materials having a Shore hardness of 70 to 90 along with theirrespective subforms (A,AE) are preferably used. Materials of othermanufacturers having comparable technical material data may be usedcorrespondingly.

The balloon, together with its shaft pieces, is bonded or fused to thecatheter shaft. In the manufacturing of the base-state balloon, thetransition regions from the shaft pieces to the central, mid-positiondiameter of the base-state balloon are designed to have wall thicknesseswhich continuously decrease from the shaft piece to the central,mid-position diameter.

It is advantageous when, after joining the balloon to the cathetershaft, the end rims of the shaft pieces are smoothed, for example, bythe action of heat or application of solvents, so that no sharp-edgedtransitions are present in the transition region from the shaft to theballoon.

In addition, when polyurethane is used for the catheter shaft, the wallthickness of the catheter shaft is advantageously smaller than inprevious designs, enabling the catheter drainage lumen to be enlarged,given the same external diameter. Thus, given a favorable materialselection, a shaft wall thickness of from 0.4 to 0.8 mm, preferably from0.4 to 0.6 mm suffices. The catheter shaft nevertheless retains itsrigidity or safety against buckling, as required for insertion into theurethra in patient applications. To further reduce the catheter wallthickness, the catheter shaft is preferably formed from twoconcentrically extruded tubes, the inner tube preferably being designedto be thinner and harder than the outer tube (co-extrusion). To achievethe same objective, a spiral reinforcement or a stabilizing mesh workedinto the shaft are also conceivable.

Moreover, the surfaces of both the balloon preferably fabricated usingthe blow-molding method and, respectively, of the preferably extrudedshaft are of highest quality when polyurethane is used. Incrustation byurinary components, as well as bacterial colonization are rendereddifficult by the special surface evenness.

The catheter described in accordance with the present invention issimple to manufacture in terms of production engineering and eliminatesthe need for cost-intensive manufacturing steps in comparison toconventional catheter types, such as, above all, latex cathetersmanufactured using the dipping method.

The catheter shaft is preferably provided with a plurality of fillingopenings in the region covered by the balloon. These filling openingshave a square, preferably rectangular shape. This substantially preventsthe thin film of the balloon from being able to close this opening orthese openings in the manner of a valve and thereby complicate theprocess of emptying the balloon.

The dimensional design of the base-state balloon is calculated, i.e.,its wall thickness is selected in a way that allows the envelope to beelastically expanded up to the working volume, while avoiding anon-elastic overstretching, i.e., the elasticity of the ballon materialis completely retained, even in the case of long-term catheter use.Therefore, once the balloon is completely drained, it clings closely tothe catheter shaft, again in longitudinal folds, as it is withdrawnthrough the urethra, and it is non-traumatizing.

The so-called suprapubic bladder catheter, another embodiment andversion of a bladder catheter that is common in practice, may likewisebe optimized by combining a polyurethane shaft with a polyurethane-basedballoon element in accordance with the present invention. When thesuprapubic catheter system is used, a hollow needle element is insertedthrough the anterior abdominal wall directly into the urinary bladder,directly above the pubic bone. The needle element may be designed as aconventional hollow needle, as a guide needle that is laterally openacross the entire length of the needle (the catheter is insertedlaterally into the guide needle), or, for example, as a so-calledspread-type needle (the hollow needle is composed of two halves whichare separable from one another by spreading).

Preformed balloon elements, in the specific embodiment according to thepresent invention of the balloon element having a working volume of 5 mlin the wall-thickness range of preferably 5 to 10 micrometers, may bepushed through the application needle when a lubricating agent is used,without having to restrict the diameter of the catheter shaft. Thus, thepatient may also benefit from the afore-mentioned advantages of abladder catheter that is manufactured in its entirety from polyurethane,when the suprapubic version is used.

It is also vitally important to the patient, who is typicallycatheterized suprapubically for extended periods of time, that thedrained balloon element be removable, to the greatest possible degreewithout causing trauma, through the puncture channel in the bladder andabdominal wall that has already healed or granulated following arelatively long catheter application.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is explained in greater detail on the basis ofexemplary embodiments illustrated in the drawings, whose figures show:

FIG. 1 a lateral, part-sectional view of the distal end of the catheter;

FIG. 2 a lateral view of the catheter prior to its insertion; and

FIG. 3 a lateral view of the catheter prior to its introduction into orwithdrawal from the urethra.

FIG. 4 shows a schematic view of the transition region from the shaftpieces to a central midposition in cross-section.

DETAILED DESCRIPTION

FIG. 1 shows the distal end of a bladder catheter 1 in a part-sectional,lateral view. Balloon element 3, which is shown in a sectional view bothas base-state balloon 4 (volume at rest) and as inflated balloon 5(working volume), is fastened to catheter shaft 2. Balloon element 3 ismade of a polyurethane-based material; in its form as base-state balloon4, it has a wall thickness of 5 to 20, preferably of 5-15 μm. It isprovided with shaft pieces 6 and 7, via which it is bonded to cathetershaft 2. At its distal end, hollow catheter shaft 2 has opening 8, viawhich urine can flow out of the urinary bladder. A filling channel 9situated in the wall of catheter shaft 2 leads to opening or pluralityof openings 10 in catheter shaft 2, which is/are placed in the region ofballoon element 3.

Once catheter 2 is introduced into the urinary bladder through theurethra, a suitable fluid, directed through channel 9 and opening(s) 10into balloon element 3, fills balloon element 3, i.e., elasticallyexpands it as it is increasingly filled from the base-state volume toits working volume.

In its completely emptied state, balloon element 3 fits on the surfaceof shaft 2, as shown in FIGS. 2 and 3.

In FIG. 2, balloon element 3 shapes itself into a fold formation 11 thatruns in the longitudinal direction of catheter shaft 2. Fold formation11 substantially extends between the two shaft pieces 6 and 7.

The fold formation permits a bulging of balloon element 3, which leadsto base-state balloon 4 shown in FIG. 1. This bulging takes placewithout any appreciable pressure and may vary in magnitude depending onthe material used. In the unexpanded, freely unfolded state, base-stateballoon 4 contains a volume at rest which is clearly less than thefilling volume contained in filled balloon 5 (working volume). Toillustrate the present invention, base-state balloon 4 is sketchedhaving a relatively large volume at rest in FIG. 1. To reduce theoverall space required by the fold formation to the greatest degreepossible, base-state balloon is mounted on the shaft in thelongitudinally oriented form. The shaft pieces of the balloon are spacedas far apart as possible, as shown in FIG. 2, without thereby tensioningthe balloon envelope.

As shown in FIG. 4, the transition region from shaft pieces 6 and 7 tothe central, mid-position section 23 of balloon 3 is kept as acontinuous, fluid transition, so that the wall thicknesses continuouslydecrease from the thickness at shaft pieces 6 and 7 to the thickness atthe central, mid-position diameter of base-state balloon 4. As shown inFIGS. 2 and 4, end rims 12 and 13 of shaft pieces 6 and 7 are smoothed,so that there is no sharp-edged transition.

As indicated in the upper portion of FIG. 2, catheter shaft 2 may becomposed of two preferably co-extruded tubes 14 and 15, which fit oneinside the other.

The lower portion of FIG. 2 shows the option of providing catheter shaft2 with a spiral reinforcement 16 of metal.

FIG. 3 shows one specific embodiment of balloon element 3, wherebase-state balloon 4 is fastened to the shaft in such a way that it isnot aligned in a fold formation, but folded randomly orunsystematically. Thus, the shaft pieces of the balloon are notmaximally spaced apart, but to a lesser degree.

The fold formation may run in any way at all, thus, for example, alsotransversely or at right angles to the catheter axis. However, since theballoon wall is exceptionally thin, once the balloon is drained, it maycling very closely to the surface of catheter shaft 2. In someinstances, hanging sack-like folds 17 or 18 form at shaft pieces 6 or 7when the catheter is inserted or removed. On the right side of FIG. 3,17 denotes a hanging sack-like fold which forms during insertion of thecatheter, and on the left side of the figure, 18 denotes a hangingsack-like fold which forms during removal of the catheter through theurethra. However, in the wall-thickness range named in accordance withthe present invention, even such hanging sack-like folds have nodisadvantageous effect during passage of the balloon element through theurethra.

1. A bladder catheter for transurethral or suprapubic introduction intoa urinary bladder comprising: a flexible catheter shaft having a wall; afilling channel defined in the catheter shaft; and a balloon elementmade of a polyurethane-based material having a Shore hardness of 70 to90 and fastened to the catheter shaft, the balloon element having a wallthickness of 5 to 20 micrometers and a preformed blow-molded shape,wherein in a first empty and unrestrained base state, the balloonelement is fitted over the catheter shaft with folds and has a firstempty volume, in a second state the balloon element is filled andunfolded without elastic expansion to a second fill volume greater thanthe first empty volume, and in a third fully formed state, the balloonelement has an elastic expansion to a third fill volume that is at leastabout double the second fill volume.
 2. The bladder catheter as recitedin claim 1, wherein the polyurethane-based material includes at leastone of a polyurethane and a polyurethane-polyvinyl chloride blend. 3.The bladder catheter as recited in claim 1, wherein the wall thicknessis 5 to 15 micrometers.
 4. The bladder catheter as recited in claim 1,wherein the balloon element in the first base state includes a pluralityof longitudinally oriented folds, the balloon element clinging to thecatheter shaft in the folded state.
 5. The bladder catheter as recitedin claim 1, wherein the balloon element in the third fully formed statehas a third fill volume of about 5 ml.
 6. The bladder catheter asrecited in claim 5, wherein the balloon element in the second filledstate has a second fill volume of 1.2 to 2.5 ml.
 7. The bladder catheteras recited in claim 6, wherein the balloon element has an empty volumeof 0.01 to 0.03 ml in the first base folded state.
 8. The bladdercatheter as recited in claim 1, wherein the balloon element has at leastone of a spherical and a spindle form.
 9. The bladder catheter asrecited in claim 1, wherein the balloon element has a third fill volumein the third fully formed state of about 30 ml.
 10. The bladder catheteras recited in claim 9, wherein the balloon element in the second filledstate has a second fill volume of 4 to 12 ml.
 11. The bladder catheteras recited in claim 9, wherein the balloon element fits on the shaft andincludes a plurality of longitudinal folds in the first base foldedstate.
 12. The bladder catheter as recited in claim 11, wherein theballoon element has an at-rest volume of less than 0.08 ml in the firstbase folded state.
 13. The bladder catheter as recited in claim 11,wherein the balloon element has a first empty volume of 0.01 to 0.03 mlin the folded state.
 14. The bladder catheter as recited in claim 1,wherein the balloon element includes a fold formation aligned inparallel with the catheter shaft and wherein the balloon element isjoined to the catheter shaft without stretching the balloon element. 15.The bladder catheter as recited in claim 1, wherein the balloon elementincludes shaft pieces fastenable to the catheter shaft, a center sectionand a transition region between the center section and the shaft pieces,and wherein a wall thickness of the balloon element continuouslydecreases from the shaft pieces to the center section.
 16. The bladdercatheter as recited in claim 15, wherein at least one shaft pieceincludes a smoothed end rim.
 17. The bladder catheter as recited inclaim 1, wherein catheter shaft includes an outer tube and an inner tubedisposed inside the outer tube.
 18. The bladder catheter as recited inclaim 17, wherein the inner tube is co-extruded with the outer tube. 19.The bladder catheter as recited in claim 17, wherein the inner tube ismade of a harder material than the outer tube.
 20. The bladder catheteras recited in claim 1, wherein the catheter shaft includes at least onefilling opening in a region of the balloon element.
 21. The bladdercatheter as recited in claim 20, wherein the at least one fillingopening has at least one of a square and a rectangular shape.
 22. Thebladder catheter as recited in claim 1, wherein the catheter shaft has aspiral reinforcement of metal.
 23. The bladder catheter as recited inclaim 1, wherein the catheter shaft is an extruded shaft.
 24. Thebladder catheter as recited in claim 1, wherein the balloon element hasa safety range of volumetric expandability of 400 to 450 percent. 25.The bladder catheter as recited in claim 1, wherein the balloon elementhas a safety range of volumetric expandability of 300 to 400 percent.26. The bladder catheter as recited in claim 1, wherein the balloonelement has a third fill volume of about 5 ml and a filling pressure of50 to 200 millibar in the third fully formed.
 27. The bladder catheteras recited in claim 1, wherein the balloon element has a volume of about30 ml and a filling pressure of 50 to 200 millibar in the third fullyformed state.
 28. The bladder catheter as recited in claim 1, whereinthe catheter is for long-term use.
 29. The bladder catheter as recitedin claim 1 wherein the balloon element in the folded state has randomlydistributed folds.
 30. The bladder catheter as recited in claim 1wherein the balloon element in the folded state has hanging sack folds.31. The bladder catheter as recited in claim 1 wherein the balloonelement in the folded state clings to the catheter shaft.
 32. Thebladder catheter as recited in claim 1 wherein the balloon elementincludes shaft pieces fastenable to the catheter shaft.
 33. The bladdercatheter as recited in claim 1 wherein the catheter shaft is made of apolyurethane-based material.
 34. The bladder catheter as recited inclaim 1 wherein the bladder catheter is for transuretheral introduction.35. A method for manufacturing the bladder catheter as recited in claim1, comprising blow-molding the polyurethane-based material having aShore hardness of 70 to 90 into the preformed shape of the balloonelement having a wall thickness of 5 to 20 micrometers.
 36. A bladdercatheter for transurethral or suprapubic introduction into a urinarybladder comprising: a flexible catheter shaft having a wall; a fillingchannel integrated into the wall; and a balloon element connected to thecatheter shaft, the balloon element being made of a polyurethane-basedmaterial having a Shore hardness of 70 to 90, the balloon element beingfillable from a folded state to a filled state, the balloon element inthe folded state disposed around the catheter shaft with unrestrainedhanging sack folds.
 37. A method for manufacturing the bladder catheteras recited in claim 36, comprising blow-molding the polyurethane-basedmaterial having a Shore hardness of 70 to 90 into a preformed shape ofthe balloon element having a wall thickness of 5 to 20 micrometers. 38.A bladder catheter for transurethral or suprapubic introduction into aurinary bladder comprising: a flexible catheter shaft having a wall; afilling channel integrated into the wall; and a balloon elementconnected to the catheter shaft, the balloon element is made of apolyurethane-based material having a Shore hardness of 70 to 90, whereinthe balloon element is fillable from a folded state to a filled state,the balloon element in the folded state disposed around the cathetershaft with randomly distributed unrestrained folds.
 39. The bladdercatheter as recited in claim 38 wherein the catheter shaft is made of apolyurethane-based material.
 40. The bladder catheter as recited inclaim 38 wherein the bladder catheter is for transuretheralintroduction.
 41. A method for manufacturing the bladder catheter asrecited in claim 38, comprising blow-molding the polyurethane-basedmaterial having a Shore hardness of 70 to 90 into a balloon elementhaving a preformed shape and a wall thickness of 5 to 20 micrometers.